A motor vehicle of the general type in question with at least one air guide device with an air guide surface which can be extended by a drive is known from DE 103 09 369 A1. The air guide surface is held by a movable positioning mechanism comprising several pivot rods supported nonrotatably on the vehicle body and designed in such a way that, when the air guide surface is in its maximally extended position, at least one pivot rod of the positioning mechanism is supported by at least one stop. The goal here is to make it possible to use smaller and less powerful drives, because even at high speeds the air guide surface is supported exclusively by a self-locking lever mechanism and no longer has to be supported by the drive device itself.
An air guide device with an air-guiding spoiler blade and with an adjusting device, which moves the spoiler blade between a rest position and an operating position as needed, is also known from DE 10 2004 043 544 B4. In the operating position, the spoiler blade is located outside the car body structure. So that the air flow can be used as effectively as possible to generate downforce for the vehicle, the spoiler blade comprises an underflow guard, which prevents the air from flowing underneath the spoiler blade. At the same time, a water guide device, which forms an integral part of the spoiler blade, is provided, which is intended to prevent as far as possible the intrusion of water into the storage well of the air guide device.
Air guide devices on motor vehicles, especially on sports cars, are sufficiently well known and usually serve to generate downforce as the vehicle is being driven to improve the vehicle's grip on the road. Air guide devices with air guide elements which are deployed as a function of speed and thus comprise a steeper angle of incidence and generate more downforce at higher speeds than at lower speeds are also known. It is known that the aerodynamics of motor vehicles depend not only on their external contour but also on additional features such as whether or not the side windows are open, the presence of rearview mirrors, etc.